﻿// Upgrade NOTE: replaced '_Object2World' with 'unity_ObjectToWorld'

// Upgrade NOTE: replaced '_World2Object' with 'unity_WorldToObject'

Shader "UnityShadersBook/Chapter06/Chapter06-SpecularVertexLevel"
{
    Properties
    {
        _Diffuse( "Diffuse", Color ) = ( 1.0,1.0,1.0,1.0 )
        _Specular( "Specular",Color ) = (1.0,1.0,1.0,1.0 )
        _Gloss( "Gloss", Range( 8.0, 256 ) ) = 20
    }
    SubShader
    {
        Tags { "LightMode" = "ForwardBase" }
        

        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            
            #include "Lighting.cginc"

            struct a2v
            {
                float4 vertex : POSITION;
                float3 normal :NORMAL;
            };

            struct v2f
            {
                float4 pos:SV_POSITION;
                fixed3 color:COLOR;
            };
            
            fixed4 _Diffuse;
            fixed4 _Specular;
            float _Gloss;

            v2f vert (a2v v)
            {
                v2f o;
                o.pos = UnityObjectToClipPos( v.vertex );

                fixed3 worldNormal = UnityObjectToWorldNormal( v.normal);          
                fixed3 worldLight = normalize( _WorldSpaceLightPos0.xyz );
                
                fixed3 diffuse = _LightColor0.rgb * _Diffuse.rgb * saturate( dot( worldNormal, worldLight ) );
                fixed3 reflectDir = normalize( reflect( -worldLight, worldNormal ) );
                fixed3 viewDir = normalize(  _WorldSpaceCameraPos.xyz - mul( unity_ObjectToWorld, v.vertex ).xyz );
                fixed3 specular = _LightColor0.rgb * _Specular.rgb * pow(saturate( dot( reflectDir, viewDir ) ),_Gloss);

                o.color = diffuse + UNITY_LIGHTMODEL_AMBIENT.xyz + specular;
                //o.color = diffuse;
                return o;
            }

            fixed4 frag (v2f i) : SV_Target
            {
                return fixed4( i.color, 1.0);
            }
            ENDCG
        }
    }

    Fallback "Diffuse"
}
